Configuration Guide User guide

1622 FastIron Configuration Guide
53-1002494-02
MLD snooping configuration
MLDv2 requires that every client respond to queries, allowing the device to track every client. When
the tracking feature is enabled, the device immediately stops forwarding traffic to the interface if
an MLDv2 client sends a leave message, and there is no other client. This feature requires the
entire VLAN to be configured for MLDv2 and have no MLDv1 clients. If a client does not send a
report during the specified group membership time (the default is 140 seconds), that client is
removed from the tracking list.
Every group on a physical port keeps its own tracking record. However, it can track group
membership only; it cannot track by (source, group). For example, Client A and Client B belong to
group1 but each is receiving traffic from different sources. Client A receives a traffic stream from
(source_1, group1) and Client B receives a traffic stream from (source_2, group1). The device waits
for the configured leave-wait-time before it stops the traffic because the two clients are in the same
group. If the clients are in different groups, the waiting period is ignored and traffic is stopped
immediately.
To enable tracking and fast leave for VLAN 20, enter the following commands.
Brocade(config)#vlan 20
Brocade(config-vlan-20)#mld-snooping tracking
Syntax: [no] mld-snooping tracking
The membership tracking and fast leave features are supported for MLDv2 only. If a port or client is
not configured for MLDv2, the mld-snooping tracking command is ignored.
Configuring fast leave for MLDv1
When a FESX or FSX device receives an MLDv1 leave message, it sends out multiple group-specific
queries. If no other client replies within the waiting period, the device stops forwarding traffic to this
port. Configuring fast-leave-v1 allows the device to stop forwarding traffic to a port immediately
upon receiving a leave message. The device does not send group-specific queries. It is important
that no snooping ports have multiple clients. When two devices connect, the querier device should
not be configured for fast-leave-v1 because the port to the non-querier device could have multiple
clients. The number of queries and the waiting period (in seconds) can be configured using the ipv6
mld-snooping leave-wait-time command. Refer to “Modifying the wait time before stopping traffic
when receiving a leave message” on page 1618.
To configure fast leave for MLDv1, use commands such as the following.
Brocade(config)#vlan 20
Brocade(config-vlan-20)#mld-snooping fast-leave-v1
Syntax: [no] mld-snooping fast-leave-v1
Enabling fast convergence
In addition to periodically sending general queries, an active (querier) FESX or FSX device sends out
general queries when it detects a new port. However, since it does not recognize the other device
port-up event, the multicast traffic might still use the query-interval time to resume after a topology
change. Configuring fast-convergence allows the device to listen to topology change events in Layer
2 (L2) protocols, such as spanning tree, and send general queries to shorten the convergence time.